Drill stem testing apparatus



Nov. 15, 1966 L. l. JENSEN 3,285,344

DRILL STEM TESTING APPARATUS Original Filed Nov. 13, 1963 [N VEIV TOR. {Mp

ATTORNEY United States Patent 3,285,344 DRILL STEM TESTING APPARATUS Lloyd 1. Jensen, Calgary, Alberta, Canada, assignor to Johnston Testers, Ltd., Calgary, Alberta, Canada, a corporation of Canada Original application Nov. 13, 1963, Ser. No. 323,490, now Patent No. 3,254,710, dated June 7, 1966. Divided and this application Dec. 20, 1965, Ser. No. 515,038 8 Claims. (Cl. 166-149) This is a division of application Serial No. 323,490 filed November 13, 1963, now Patent No. 3,254,710.

This invention relates to formation testing and, more particularly, to methods and apparatus for obtaining recovery of fluid samples from a well bore.

In the exploration for oil it is often desirable to conduct a drill stem test in a well bore while it is being drilled for potential hydrocarbon production. In a drill stem test, a testing tool is inserted into the well bore at the lower end of a string of pipe or tubing. After packing off or isolating the formations to be tested from the well control fluid (usually called mud), the tester valve is opened so that any fluids from the formations may flow into the string of tubing. Thus when a fluid flow occurs, there are clear visual indications at the surface.

It is well known that much exploration is conducted under utmost secrecy. For this reason, when conducting a drill stem test on a well it is highly desirable to maintain the results of the test strictly confidential.

In accordance with the present invention, in a drill stem test, the fluid recovery is limited to a given sampling section of the drill pipe which is closed off prior to retrieving the sampling section at the earths surface. The closed off sampling section when retrieved is separated into individual sample containers which are usually a length of drill pipe. Into each end of a drill pipe prior to separation, a neutral displacement agent is injected to displace any trace of fluid recovery from the ends of the pipe and the pipe ends are sealed before separation. Thereafter, upon separation, the fluid recovery in a sealed pipe length can be transported to any suitable or desired location for examination in the privacy of a laboratory.

Apparatus in accordance with the present invention includes end connections called subs which attach to the joint of the pipe and to one another. Means are provided for injecting a neutral displacement agent to the interconnection between coupled subs and sealing off the passages in the subs after the fluid sample has been displaced.

Accordingly, it is an object of the present invention to provide new and improved apparatus and methods for conducting drill stern tests where the results of the test can be confined between sealed ends of a container or length of drill pipe.

Still another object of the present invention is to provide new and improved methods and apparatus for conducting drill stem tests to obtain discrete fluid samples between the ends of a length of drill pipe.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a string of tools in a well bore for practicing the present invention;

FIG. 2 illustrates a view in cross-section of apparatus embodied in the present invention; and

FIG. 3 is a view taken along line 33 of FIG. 2.

ICC

FIGURE 1 illustrates apparatus embodying the invention where a drill or tubing string 11 is lowered from the surface of the earth into a well bore 12. At the lower end of the drill string 11 is a conventional testing tool string 13 such as the type illustrated and described in US. Patent Number 2,901,001. The usual drill stem testing tool string 13 includes a flow tube with a normallyclosed valve (not shown) and a packer element 14. The packer element 14, when actuated, expands into sealing engagement with the borehole wall. After the tester valve is opened, fluid flows from below the packer 14 through its flow tube and into the tubing string. Pressure recorders (not shown) in the tool string 13 measure and record pressures. As shown in FIG. 1, a perforated anchor 15, for admitting well fluid to the flow tube is also used for engaging the bottom of the well bore for expanding the packer in a conventional manner.

It will be appreciated that hook-wall packers (not shown) which can be set without a bottom hole anchor could be employed rather than the type described.

In the present invention, one or more of the tubing string sections 1648 adjacent to the tester 13 are separated from one another by a pair of releasably connected isolation subs A and B. These isolation subs, as will hereinafter be more fully explained, serve to enclose within the ends of a section of tubing a fluid sample so that there is no external indication of the presence or absence of fluid when the subs are disconnected at the surface. The enclosed fluid samples then can be safely transported to any suitable location for a private examination and analysis.

Referring now to FIGURE 2, each isolation sub A and B has a similar construction including threaded box and pin ends 19 and 20 for connection in a string of tubing. Each sub has similar longitudinal flow passages 21a and 21b extending longitudinally through the respective subs and each has a similar valve 22a and 22b provided for the respective passages. Valve 22a, shown in its normally open position, has a body portion 23a threadedly received in a valve bore 24a and has a tapered valve portion 25a provided with 0 rings. When the valve body 23a is rotated, the valve portion 25a seats in a valve seat 26a in a sub unit to block or close off the fluid passageway 21a. Rotation of the valve body 23a is accomplished by means of a wrench or the like applied to the body 23a through a cylinder bore 27a opening to the exterior. Thus, the valve has a control portion exposed to the exterior of the sub. The body portion 230! of a valve 22a is provided with an O ring to seal within a cylinder bore 27a. A snap ring 28a received in a snap ring groove prevents the valve body from leaving the valve bore 27a. Valve 22b has a simi a arrangement.

The lower sub unit B is provided with another valve 30 (FIG. 3) which controls fluid flow to a passageway 31 in fluid communication with and opening to the longitudinal passageway 21b. The valve 30 which is normally closed, includes a body 32 threadedly received in a bore 33 with a valve element 34 having 0 rings providing a seal with a valve seat 35 in the sub. The valve body 32 similarly is provided with an O ring 36 and snap ring retainer 37 and similarly is controlled from the exterior of the sub. Another transverse passage 38 opens midway of the valve body 32 and is connected to a conventional pressure fitting unit 39. When the valve 30 is opened, as by unthreading of the valve body, the pressure fitting 39 and the transverse bore 31 are placed in fluid communication.

In the apparatus as thus far described, well fluid can flow through the tester 13 through the sub units A and B and into the various sections 1618 of tubing string. At the upper end of the testing section above the uppermost isolation sub, a relief valve 40 is provided. As shown in FIG. 2 the relief valve 40 includes a generally cylindrical housing 42 with a longitudinally extending bore 43 having upper and lower counterbore sections 44 and 45. In the lower end of the housing 42, the counterbore 45 is closed by a ported plug 46 which has an upwardly facing valve seat 47. An undersized cylindrical element 48 is disposed within the lower counterbore 45 and has a downwardly facing valve surface 49 provided with an O ring. A spring element 50 is provided to normally urge the cylindrical element 48 to a position closing the port in the plug 46. When the cylindrical element is displaced from the plug 47, the annulus 51 between the cylindrical element 48 and counterbore 45 permits a fluid bypass. The cylindrical element 48 is provided with up standing spacer elements 52 to maintain the bore 43 open when the cylindrical element 48 is pushed upwardly. The central bore is connected by transverse ports 53 to the exterior of the housing 42.

The trip or relief valve 40 has a plunger element 54 with portions 55 and 56 respectively received in the upper counterbore 44 and central bore 43. The plunger element 54 is held in the upper position by a shear ring 57. A hammer portion 58 of the plunger element 54 when struck with a go-devil or the like dropped through a tubing string shears the ring 57 and displaces or transfers the plunger portion 55. to a second position. The portion 56 of the plunger in the central bore 43 is provided with spaced ring seals 59 which straddle the transverse ports 53 in the second position of the plunger and thereby close the ports from fluid flow. A depending portion 60 of the plunger element is arranged to engage the upper end of the cylindrical element 48 in the second portion to limit downward travel of element 54 and insure the proper positioning of seals 59 to either side of ports 53.

In operation, the test tool string 13 is lowered into the well bore, at the end of a string of tubing or pipe, the test valve of the tool string 13 being closed. Above tool string 13 are sections of tubing 16, 17, 18 each having a sub-unit A and B respectively secured to the ends. Adjacent sub-units A and B are threadedly interconnected. At the top of the test sections of tubing, a relief valve 40 is connected above a sub-unit A.

At the level where the test is desired, the packer is actuated into sealing engagement with the well bore and the test valve of tool string 13 opened permitting formation fluids isolated below the packer to flow into the tubing sections 16-18. The hydrostatic pressure of the well fluid (mud) above the packer acts on element 48 in the relief valve to keep the valve closed. Thus, a fluid sample is recovered within sections 16-18 only, the flow upwardly into the tubing string being prevented by relief valve 40.

After permitting fluid to flow for a suitable period of time, the test valve of the tool string 13 is closed thus closing off the ends of the sampling section and the packer disengages from the well bore.

While the tubing string is being retrieved from the well bore, if the pressure of the fluids within sections 16-18 'ceeds-the hydrostatic pressure, the relief valve 40 allows th fluid under pressure in the tubing sections 16-18 to eed off into the annulus. Because of the large volumes theltest results. At a point where the relief valve is about feetbelow the surface, a go-devil is dropped through the tubing string and engages the hammer element in the reliefvalve to retain the relief valve in a closed position. The seals 59, of the relief valve thus positively close off relief valve and first subs A and B are then brought here'they are available for disconnection. is opened and a grease gun or any gv a neutral displacement agent is re sure fitting 39. Grease is injected dsbet een'subs A and B. Following f;. subs.A and B are closed. It

of mud, this bleed off is but a trace and does not reveal is noted that it may be desirable to sequence the steps as follows: initially close valve 22b of sub unit B and permit grease flow into passageway 21a of sub A; close valve 220 of sub A; open valve 22b of sub B for injection of grease followed by closing of valve 22b of sub B.

After displacing the recovery fluid from the releasably interconnected subs A and B with a neutral agent, the threaded connection between the sub-units A and B is broken. The lower set of isolation on the joint of pipe is then brought to the surface. Valve B is closed and, as described above, a suitable neutral displacement agent is pumped via valve 30 to displace any recovery fluid between the units through sub A. Thereafter, the valve 22a of sub A is closed, valve 22b of sub B is opened and displacement fluid injected followed by closing of valve 22b in sub B. The threaded connection between the subunits A and B is then broken.

It will be appreciated that the disconnected section of tubing 18 contains a fluid sample between sub-units A and B at its opposite ends and no visual indication of the presence or absence of a fluid sample is given. Each section of the tubing is thus individually isolated and individually sealed samples are obtained. Each individual sample in a tubing string then can be transported to any desired location and the sample analyzed in privacy.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. Apparatus for use in a string of drillstem testing tools comprising: a sub having short length and having ends arranged for interconnection in a string of pipe; said sub having a first longitudinal passage extending therethrough; a first valve means for selectively opening and closing said first passage; said first valve means having a control portion thereof exposed to the exterior of said su-b, said control portion being adapted for exter-ior control of operation of said first valve means; said sub having a second passage extending transversely through said sub to provide fluid communcation between said first passage extending longitudinally through said sub and the exterior of said sub and string of tools; second valve means for selectively opening and closing said second passage; said second valve means having a control portion thereof exposed to the exterior of said sub,

said control portion being adapted for exterior control of operation of said second valve means.

2. Apparatus for use in testing tools comprising: a 'sub having short length and having ends arranged for interconnection in a string of pipe; said sub having a longitudinal bore extending therethroughwith upper and lower counterbores; said lower counterbore having a ported closure, a first valve element slidably received in said lower counterbore for closing said ported closure; a passage in said sub connecting the exterior of said sub to said lower counterbore whereby well fluid exterior of said sub may retain said first valve element in a position closing said ported closure 50 long as the pressure of the well fluid exceeds a pressure on said ported closure; a second valve element normally displaced from a position closing said passage and slidably received in said longitudinal bore, said second va-lve element having an upwardly extending portion adapted to be struck by a godevil or the like for transfer to a position closing said passage.

3. The apparatus of claim 2 wherein said second valve element has a depending portion engageable with said first valve element when said second valve element closes said passage to limit its downward travel.

4. A subcombination for use in a drill string comprising a pair of releasably coupled subs each having a short length and remaining ends for connection with tubular members, each of said subs having a longitudinal passage extending therethrough, each of said subs have independently selectively operable first valve means for opening and closing said passage, said first valve means each having a control portion thereof exposed to the exterior of a sub, said control portion being adapted for exterior control of operation of said first valve means, at least one of said subs having another passage in fluid communication with the longitudinal passage between the coupled subs, second valve means in said other passage for opening and closing said other passage, said second valve means having a control portion exposed to the exterior of a sub, said control portion being adapted for exterior control of operation of said second valve means.

5. The apparatus of claim 4 wherein said subcombination further includes another sub, said other sub being coupled to one of said pair of subs and having a passage to the exterior, third valve means in said other sub for closing said last mentioned passageway.

6. In a string of tools including a selectively operable test valve and packer means in conjunction with said valve for isolating a formation and selectively flowing formation fluid into the interior of said string of tools to test a well, the combination of means for maintaining formation fluids substantially confined to the interior of said string of tools when said string of tools is brought to the surface, which means comprises: a sample chamber in said string of tools to receive said formation fluid; subs of short length connected to each end of said sample chamber, said subs having a longitudinal passage extending therethrough; selectively operable valve means in each of said subs for opening and closing said longitudinal passage in said subs; said valve means having a control portion exposed to the exterior of said sub, said control portion being adapted for exterior control of operation of said valve means; and a second transverse passage and valve in said subs, said second passage connecting the exterior of said subs with said longitudinal passage; said valve in said second passage also having a control portion exposed to the exterior of said sub permitting operation of said valve in said second passage from the exterior of said string of tools.

7. The apparatus of claim 6 wherein said sample chamber is comprised of at least one section of pipe.

8. In a string of tools including a selectively operable test valve and packer means in conjunction with said valve for isolating a formation and selectively flowing formation fluid into the interior of said string of tools to test a well, the combination of means for maintaining formation fluids substantially confined to the interior of said string of tools when said string of tools is brought to the surface, which means comprises: a sample chamber in said string of tools to receive said formation fluid; subs of short length connected to each end of said sample chamber, said subs having a longitudinal passage extending therethrough; selectively operable valve means in each of said subs for opening and closing said longitudinal passage in said subs; said valve means having a control portion exposed to the exterior of said sub, said control portion being adapted for exterior control of operation of said valve means; and a second transverse passage and valve in at least one of said subs, said second passage connecting the exterior of said subs with said longitudinal passage; said valve in said second passage also having a control portion exposed to the exterior of said sub permitting operation of said valve in said second passage from the exterior of said string of tools.

References Cited by the Examiner UNITED STATES PATENTS 272,286 2/ 1883 Manchester 137-614 1,437,136 11/1922 Freer 137-614 1,634,813 7/1927 Whitehead 137-614 X 2,176,240 10/1939 Bandy 166-164 3,075,585 1/1963 Carlton et al 166-164 3,217,806 11/1965 Voetter 166-16-3 CHARLES E. OCONNELL, Primary Examiner.

D. H. BROWN, Assistant Examiner. 

1. APPARATUS FOR USE IN A STRING OF DRILLSTEM TESTING TOOLS COMPRISING: A SUB HAVING SHORT LENGTH AND HAVING ENDS ARRANGED FOR INTERCONNECTION IN A STRING OF PIPE; SAID SUB HAVING A FIRST LONGITUDINAL PASSAGE EXTENDING THERETHROUGH; A FIRST VALVE MEANS FOR SELECTIVELY OPENING AND CLOSING SAID FIRST PASSAGE; SAID FIRST VALVE MEANS HAVING A CONTROL PORTION THEREOF EXPOSED TO THE EXTERIOR OF SAID SUB, SAID CONTROL PORTION BEING ADAPTED FOR EXTERIOR CONTROL OF OPERATION OF SAID FIRST VALVE MEANS; SAID SUB HAVING A SECOND PASSAGE EXTENDING TRANSVERSELY THROUGH SAID SUB TO PROVIDE FLUID COMMUNICATION BETWEEN SAID FIRST PASSAGE EXTENDING LONGITUDINALLY THROUGH SAID SUB AND THE EXTERIOR OF SAID SUB AND STRING OF TOOLS; SECOND VALVE MEANS FOR SELECTIVELY OPENING AND CLOSING SAID SECOND PASSSAGE; SAID SECOND VALVE MEANS HAVING A CONTROL PORTION THEREOF EXPOSED TO THE EXTERIOR OF SAID SUB, SAID CONTROL PORTION BEING ADAPTED FOR EXTERIOR CONTROL OF OPERATION OF SAID SECOND VALVE MEANS. 